1. Field of the Invention
The present invention relates to a matching circuit and an antenna apparatus employing the same and, more particularly, to a matching circuit and an antenna apparatus for use in a radio apparatus which transmits and receives radio waves having a wide range of frequencies, for example, a television, a radio or a pager.
2. Description of the Related Art
Generally, as antenna bodies used in radio apparatus which transmit and receive radio waves having a wide range of frequencies, for example, televisions (90 to 800 MHz), there are Yagi and Uda antennas, whip antennas and the like. However, in the case of Yagi, Uda and whip antennas, since the bandwidth is widened so as to receive radio waves having a wide range of frequencies, the antenna become greatly enlarged.
As compared with the above antennas, an antenna apparatus 50 shown in FIG. 8 has been proposed to achieve a small size. Shown in FIG. 8 are an antenna body 51, a mounting board 52 for mounting the antenna body 51, grounding patterns 53 formed on the mounting board 52, and a transmission line 54 formed similarly on the mounting board 52. The grounding patterns 53 are connected to a ground. Further, the transmission line 54 is connected to a power source V, and the power source V is connected to a ground.
For example, this antenna body 51, as shown in FIG. 9, comprises a rectangular-parallelopiped insulator 55 in which insulator layers (not shown) made of insulator powder of alumina, steatite or the like are laminated, a conductor 56, made of silver, silver-palladium or the like, formed in a coil shape inside the insulator 55, a magnetic substance 57, made of magnetic powder of ferrite powder or the like, formed inside the insulator 55 and the coil-shaped conductor 56, and external connection terminals 58a and 58b which are coated and printed to the extension end (not shown) of the conductor 56 after the insulator 55 is baked.
However, in the above-described conventional small-sized antenna apparatus, the bandwidth is narrow, and therefore, the antenna apparatus cannot be used in a radio apparatus which transmits and receives radio waves having a wide range of frequencies.
The present invention has been achieved to solve the above-described problem. It is an object of the present invention to provide a matching circuit and an antenna apparatus employing the same, which, though small-sized, can be used in a radio apparatus which transmits and receives radio waves having a wide range of frequencies.